1. Field of the Invention
This invention relates in general to an apparatus for checking printed circuit wiring which are arranged, for example, on printed circuit boards.
2. Description of the Prior Art
Extensive miniaturization in electronics has required smaller and smaller printed board circuits particularly for multiple layer circuits and this results in a decrease in size of the grid dimensions of the terminal points.
So-called needle adapters have been employed for electrically checking printed circuit boards wherein a resilient contact pin mounted in the needle adapters at each grid point in a carrier block serves as a grid member which contacts the circuit points. These prior art contacting devices consist of pins which are spring biased with separate pressure springs. The ends of the pins which contact the contact locations are shaped into a point or knife edge so as to guarantee good electrical contact. The other ends of the pins are connected to flexible electrical conductors which are connected to outer electrical terminals of the testing device.
Such testing devices have the disadvantage that due to the space requirements of the individual contact elements considerable problems occur in that in making the contacts smaller and smaller makes it difficult to mount such needle adapters. For example, with grid dimensions below 1 mm definite limits are reached for using such checking devices. The electrical checking of printed circuit boards with these small dimensions has not been successfully accomplished to the present time.